Stacked structure, magnetoresistance effect element, magnetic head, sensor, high frequency filter, and oscillator

Abstract

The layered structure according to the present application is a layered structure on a non-magnetic metal layer (5B), and has a ferromagnetic layer (6) and an intermediate layer (5C) interposed between the non-magnetic metal layer (5B) and the ferromagnetic layer (6), the intermediate layer (5C) containing a NiAlX alloy layer represented by general formula (1). Ni γ1 Al γ2 X γ3 …(1) [X represents one or more elements selected from the group consisting of Si, Sc, Ti, Cr, Mn, Fe, Co, Cu, Zr, Nb, and Ta, and in the case of γ = γ3 / (γ1+γ2+γ3), 0 < γ < 0.5 is satisfied.]

Description

[0001] (This application is a divisional application of patent application No. 201811113397.X, filed on September 25, 2018, and entitled “Laminated Structure, Magnetoresistive Element, Magnetic Head, Sensor, High-Frequency Filter, and Oscillator.”) Technical Field

[0002] The present invention relates to a stacked structure, a magnetoresistive effect element, a magnetic head, a sensor, a high-frequency filter, and an oscillator. Background Art

[0003] In recent years, giant magnetoresistance (GMR) elements, which consist of a multilayer film of a ferromagnetic layer / non-magnetic metal layer, and tunnel magnetoresistance (TMR) elements, which consist of a ferromagnetic layer / insulator layer / ferromagnetic layer, have attracted attention as basic functional elements in various devices. TMR elements are used in ferromagnetic spin tunnel junction (MTJ) elements, etc. These elements can also be applied to new magnetic field sensors or non-volatile random access memory (MRAM) elements, and are also expected to be applied to spin injection elements. Spin injection elements are related to having a surface recording density of terabit class and are an element that utilizes the spin accumulation effect, which is expected to achieve high resolution and high output. In the TMR element described in Patent Document 1, an MgO layer is present as a barrier layer between the non-magnetic metal layer and the ferromagnetic layer. Furthermore, as described in Non-Patent Document 1, there is known a technique for using Cu as a non-magnetic metal layer in a GMR element in which a non-magnetic metal layer is disposed between ferromagnetic layers.

[0004] Existing patent literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 5416781

[0007] Non-patent literature

[0008] Non-patent document 1: PHYSICAL REVIEW B 81, 184431 (2010) Summary of the Invention

[0009] The above-mentioned structure has a high spin injection efficiency, but a structure that can further improve the spin injection efficiency is desired. The present invention has been completed in response to such technical problems, and its purpose is to provide a stacked structure that can improve the spin injection efficiency when applied to a magnetoresistive effect element, a magnetoresistive effect element, a magnetic head, a sensor, a high-frequency filter, and an oscillator.

[0010] After conducting specialized research, the inventors of this application discovered that directly bonding a non-magnetic metal layer to a ferromagnetic layer increases the size of the dead layer, which does not perform a magnetic action, and does not improve the spin injection efficiency. Furthermore, they discovered that using a NiAlX alloy layer (X is a specified metal or semiconductor) between the non-magnetic metal layer and the ferromagnetic layer can improve the spin injection efficiency. By using a NiAlX alloy layer that mitigates the lattice mismatch between the non-magnetic metal layer and the ferromagnetic layer, the crystal quality of these layers can be improved, and the area of ​​the dead layer, which does not perform a magnetic action, can be reduced. This improves the spin injection efficiency when used in magnetoresistive elements.

[0011] In order to solve the above technical problems, the first stacked structure is a stacked structure located on a non-magnetic metal layer, and includes a ferromagnetic layer and an intermediate layer between the non-magnetic metal layer and the ferromagnetic layer, wherein the intermediate layer includes a NiAlX alloy layer represented by the following general formula (1).

[0012] Ni γ1 Al γ2 X γ3 ……(1)

[0013] [X represents one or more elements selected from Si, Sc, Ti, Cr, Mn, Fe, Co, Cu, Zr, Nb, and Ta, and when γ = γ3 / (γ1 + γ2 + γ3), 0 < γ < 0.5 is satisfied.]

[0014] In this laminated structure, the NiAlX alloy represented by the general formula (1) is laminated so that the lattice mismatch between the ferromagnetic layer and the non-magnetic metal layer is reduced compared to a case where only the ferromagnetic layer and the non-magnetic metal layer are laminated. Therefore, according to this laminated structure, the non-inductive layer on the ferromagnetic layer and the non-magnetic metal layer is reduced.

[0015] In this case, the presence of the intermediate layer mitigates the lattice mismatch between the non-magnetic metal layer and the ferromagnetic layer. This improved crystallinity reduces the area of ​​the non-inductive layer. Consequently, the area of ​​magnetic interaction increases, improving spin injection efficiency. In particular, when γ is within the above range, the non-inductive layer area becomes particularly small.

[0016] In the second stacked structure, the value of γ3 varies along the in-plane or thickness direction. Specifically, by setting the value of γ3 to mitigate the local lattice mismatch and varying the X element concentration, the quality of the ferromagnetic and nonmagnetic metal layers can be expected to improve.

[0017] In the third stacked structure, when L is set to one or more elements selected from Mn and Fe, M is set to one or more elements selected from Si, Al, Ga, and Ge, and α and β are set to positive values, the ferromagnetic layer includes a Heusler alloy represented by the following general formula (2). When the ferromagnetic layer is a Heusler alloy, the spin polarization becomes higher and the spin injection efficiency becomes higher.

[0018] Co2L α M β ……(2)

[0019] In addition, when L and M are the above-mentioned elements, the Heusler alloy serving as the ferromagnetic layer has a lattice constant corresponding reference value close to that of the NiAlX alloy layer represented by general formula (1). In addition, the number of the above-mentioned elements is not 1, because even if it is 1 or more, it is easy to infer that it has a lattice constant close to that of the NiAlX alloy layer, so the crystallinity and magnetic quality of the ferromagnetic layer can be well maintained. As a result, the non-inductive layer in the ferromagnetic layer and the non-magnetic metal layer can be further reduced. In addition, the so-called lattice constant corresponding reference value here refers to either the lattice constant a or the value of 2 times a when each crystal plane is matched at a 0-degree tilt, and refers to the value obtained by multiplying a by the square root of 2 when matching at a 45-degree tilt.

[0020] In the fourth stacked structure, the value of γ3 decreases as the distance from the ferromagnetic layer increases along its thickness direction. In this stacked structure, compared to a stacked structure consisting solely of ferromagnetic layers, the NiAlX alloy layer represented by general formula (1) has a higher X element concentration on the ferromagnetic layer side, resulting in a smaller lattice mismatch between the ferromagnetic layer and the nonmagnetic metal layer. Furthermore, because the X element concentration is lower on the nonmagnetic metal layer side, the lattice mismatch between the ferromagnetic layer and the nonmagnetic metal layer is further reduced. Consequently, this stacked structure further reduces the area of ​​the non-inductive layer within the ferromagnetic layer and the nonmagnetic metal layer.

[0021] In the fifth stacked structure, the nonmagnetic metal layer contains one or more elements selected from Ag, Cr, Al, Au, and NiAl. This nonmagnetic metal layer can easily suppress the diffusion of element X into the nonmagnetic metal layer. It is believed that the element with a low diffusion coefficient for element X does not need to be a single element; the diffusion suppression effect can be achieved by using at least one element.

[0022] In the sixth stacked structure, X in the NiAlX alloy layer is one or more elements selected from Si, Cr, Fe, Co, and Zr. In this stacked structure, the lattice constant correspondence reference value of the ferromagnetic layer is maintained at ≤ the lattice constant correspondence reference value of the NiAlX alloy layer ≤ the lattice constant correspondence reference value of the non-magnetic metal layer; or the lattice constant correspondence reference value of the ferromagnetic layer is maintained at ≥ the lattice constant correspondence reference value of the NiAlX alloy layer ≥ the lattice constant correspondence reference value of the non-magnetic metal layer. This alleviates the lattice mismatch between the ferromagnetic and non-magnetic metal layers. The lattice constant correspondence reference value here refers to either the lattice constant a or twice a when the crystal planes are aligned at a 0-degree inclination; and to a times the square root of 2 when the crystal planes are aligned at a 45-degree inclination. Therefore, this stacked structure reduces the size of the non-inductive layers in the ferromagnetic and non-magnetic metal layers. This relationship between the lattice constant correspondence reference values ​​holds true even when the number of elements is one or more.

[0023] In the seventh stacked structure, in general formula (1), 0 < γ < 0.3 is satisfied. When γ is within this range, the area of ​​the non-inductive layer is further reduced. Furthermore, in this stacked structure, the crystal structure of the NiAlX alloy layer is stable, and a face-centered cubic lattice structure can be obtained. As a result, the lattice mismatch between the ferromagnetic layer and the non-magnetic metal layer can be alleviated, and the area of ​​the non-inductive layer can be reduced.

[0024] In the eighth stacked structure, when the thickness of the NiAlX alloy layer is set to t1, 0.2 nm ≤ t1 ≤ 10 nm is satisfied. With this stacked structure, when t1 ≤ 10 nm, spin scattering for electrons migrating from and to the ferromagnetic layer is further reduced. Furthermore, when 0.2 nm ≤ t1, the lattice mismatch between the ferromagnetic layer and the nonmagnetic metal layer is further reduced. As a result, the non-inductive layer in the ferromagnetic and nonmagnetic metal layers is reduced.

[0025] In the ninth stacked structure, in the Heusler alloy represented by the above-mentioned general formula (2), α and β satisfy the following relational expressions (2-1), (2-2), and (2-3).

[0026] 0.7<α<1.6……(2-1)

[0027] 0.65<β<1.35……(2-2)

[0028] 2<α+β<2.6……(2-3)

[0029] With this stacked structure, the ferromagnetic layer (Heusler alloy) has a lattice constant close to that of a stoichiometric composition, as 0.7 < α < 1.6 and 0.65 < β < 1.35, resulting in improved lattice matching. Furthermore, because 2 < α + β < 2.6, the ferromagnetic layer (Heusler alloy) easily maintains half-metallic properties and achieves a high magnetoresistance effect (MR ratio).

[0030] The magnetoresistive effect element according to the present invention includes any of the aforementioned stacked structures, and the magnetic head, sensor, high-frequency filter, and oscillator according to the present invention each include the aforementioned magnetoresistive effect element.

[0031] Furthermore, if electron spin can be utilized, the area of ​​the non-sensitive layer can be reduced, so the stacked structure can also be applied to applications other than magnetoresistive elements (the so-called spin Hall effect / inverse spin Hall effect, and spin transfer torque technology).

[0032] According to the present invention, a stacked structure, a magnetoresistive element, a magnetic head, a sensor, a high-frequency filter, and an oscillator capable of improving spin injection efficiency can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a front view of the magnetoresistive effect element MR according to the embodiment.

[0034] Figure 2 It is a front view of a magnetoresistive effect element MR according to a comparative example.

[0035] Figure 3 This is a graph showing the relationship between γ in the intermediate layer made of NiAlX alloy and the non-sensitive layer.

[0036] Figure 4 This is a graph showing the thickness of the non-inductive layer and the like in magnetoresistive elements (Comparative Example, Examples 1 to 5) when various materials are used.

[0037] Figure 5 This is a graph showing the relationship between the thickness t1 (nm) of the intermediate layer and the thickness t2 (nm) of the non-sensitive layer in Example A group.

[0038] Figure 6 This is a graph showing the relationship between the thickness t1 (nm) of the intermediate layer and the thickness t2 (nm) of the non-sensitive layer in Example A group.

[0039] Figure 7 It means that in Example B, the ferromagnetic layer (Co2L α M β) is a graph showing the relationship between various parameters (α+β, α, β) and MR ratio (%) (β is constant).

[0040] Figure 8 It means that in Example C, the ferromagnetic layer (Co2L α M β ) is a graph showing the relationship between various parameters (α+β, α, β) and MR ratio (%) (α is constant).

[0041] Figure 9 This is a graph showing the relationship between α+β and MR ratio (%) in Example B group and Example C group.

[0042] Figure 10 This is a graph showing the lattice constants, structure types, and Pearson symbols of Ag and NiAlX alloys.

[0043] Figure 11 This is a graph showing the lattice constants, structure types, and Pearson symbols of Ag and NiAlX alloys.

[0044] Figure 12 This is a graph showing the lattice constants of various Heusler alloys.

[0045] Figure 13 This is a graph showing the lattice mismatch rates of Ag or NiAlX alloys and various Heusler alloys.

[0046] Figure 14 This is a graph showing the lattice mismatch rates of Ag or NiAlX alloys and various Heusler alloys.

[0047] Figure 15 This is a graph showing the lattice mismatch rates of Ag or NiAlX alloys and various Heusler alloys.

[0048] Figure 16 This is a graph showing the lattice mismatch rates of Ag or NiAlX alloys and various Heusler alloys.

[0049] Figure 17 Schematic diagram showing the cross-sectional structure of a playback portion of a magnetic head having a magnetoresistive element.

[0050] Figure 18 A diagram showing a cross-sectional structure of a magnetic head having a magnetoresistive element.

[0051] Figure 19 A diagram showing the structure of a current sensor including a plurality of magnetoresistive effect elements.

[0052] Figure 20 This is a diagram showing the structure of a high-frequency filter including a plurality of magnetoresistive effect elements.

[0053] Figure 21 It means that Figure 1 Graph showing materials, lattice constants, film thicknesses, and MR ratios (%) in the case of deformation.

[0054] Explanation of symbols

[0055] 4...the first ferromagnetic layer

[0056] 6...Second ferromagnetic layer

[0057] 5... non-magnetic spacer layer

[0058] 5B... non-magnetic metal layer

[0059] 5A...1st intermediate floor

[0060] 5C...Second Intermediate Layer DETAILED DESCRIPTION

[0061] The following describes the magnetoresistive effect element according to the embodiment. Identical elements are denoted by the same reference numerals, and duplicate descriptions are omitted. In a three-dimensional rectangular coordinate system, the thickness direction of each layer is defined as the Z-axis, and the two perpendicular axes perpendicular to the Z-axis are defined as the X-axis and the Y-axis.

[0062] Figure 1 It is a front view of the magnetoresistive effect element MR according to the embodiment.

[0063] The magnetoresistive element MR comprises a first nonmagnetic metal layer 2 and a second nonmagnetic metal layer 3, sequentially arranged on a first base layer 1. A first ferromagnetic layer 4, serving as a fixed magnetization layer, a nonmagnetic spacer layer 5, and a second ferromagnetic layer 6, serving as a free magnetization layer, are stacked on top of these layers. A protective nonmagnetic metal layer 7 and a contact metal layer 8 are sequentially formed on the second ferromagnetic layer 6, although the protective nonmagnetic metal layer 7 may be omitted. Applying a bias voltage between the lower first nonmagnetic metal layer 2 or second nonmagnetic metal layer 3 and the upper contact metal layer 8 allows electrons with a specific spin direction to flow perpendicular to the film surface.

[0064] When the magnetization directions of the fixed and free layers are the same (e.g., +X, +X) (parallel), electrons with spins in the same direction pass perpendicularly through the film surface. When the magnetization directions of the fixed and free layers are opposite (e.g., +X, -X) (antiparallel), electrons with spins in the opposite direction are reflected and do not pass through the film surface.

[0065] The magnetization direction of the first ferromagnetic layer 4 (magnetization pinned layer) is fixed, while the magnetization direction of the second ferromagnetic layer 6 (magnetization free layer) can be changed by an external magnetic field. Therefore, the amount of electrons passing through the layer varies according to the magnitude of the external magnetic field. A high amount of electrons passing through the layer results in low resistance, while a low amount of electrons passing through the layer results in high resistance. Because the first ferromagnetic layer 4, acting as the magnetization pinned layer, is thicker than the second ferromagnetic layer 6 and its magnetization direction is more difficult to change by an external magnetic field than the first ferromagnetic layer 4, it essentially functions as a magnetization pinned layer with a fixed magnetization direction. Another indicator used to evaluate the performance of magnetoresistive elements is the MR ratio. The MR ratio is calculated as [(the resistance value of the element when the magnetization directions are antiparallel - the resistance value of the element when the magnetization directions are parallel) / the resistance value of the element when the magnetization directions are parallel].

[0066] In addition, Figure 1 For ease of understanding, representative material names used are indicated in each layer, but other materials may also be applied to each layer.

[0067] A nonmagnetic spacer layer 5 is provided between the first ferromagnetic layer 4 and the second ferromagnetic layer 6. The nonmagnetic spacer layer 5 comprises at least one of a nonmagnetic metal layer 5B composed of Ag, a first intermediate layer 5A provided on the lower surface of the nonmagnetic metal layer 5B, and a second intermediate layer 5C provided on the upper surface of the nonmagnetic metal layer 5B. In other words, even if one of the first intermediate layer 5A and the second intermediate layer 5C is omitted, the central nonmagnetic metal layer 5B can be configured to be in contact with either the upper or lower ferromagnetic layer.

[0068] The first intermediate layer 5A and the second intermediate layer 5C include a NiAlX alloy layer represented by the following general formula (1).

[0069] General formula (1): Ni γ1 Al γ2 X γ3 ……(1)

[0070] Here, X represents one or more elements selected from Si, Sc, Ti, Cr, Mn, Fe, Co, Cu, Zr, Nb and Ta, and satisfies 0<γ<0.5 when γ=γ3 / (γ1+γ2+γ3).

[0071] That is, in addition to NiAlX alloys composed of combinations of Ni-Al-Si, Ni-Al-Sc, Ni-Al-Ti, Ni-Al-Cr, Ni-Al-Mn, Ni-Al-Fe, Ni-Al-Co, Ni-Al-Cu, Ni-Al-Zr, Ni-Al-Nb, Ni-Al-Ta, etc., NiAlX alloys such as V-Ni-Al, Ni-Al-Ge, Ni-Al-Sn, Ni-Al-Sb, Hf-Ni-Al, etc., which have electrical properties and lattice constants close to those of these alloys in crystal structure, can also be used.

[0072] In this case, the lattice matching between any of the intermediate layers (the first intermediate layer 5A, the second intermediate layer 5C) comprising the NiAlX alloy layer and the non-magnetic metal layer 5B comprising Cu or Ag, etc. becomes higher. In addition, since the lattice matching between the intermediate layers (the first intermediate layer 5A, the second intermediate layer 5C) and the ferromagnetic layers (the first ferromagnetic layer 4, the second ferromagnetic layer 6) located outside them may also be improved, the area of ​​the above-mentioned non-inductive layer can be reduced and the spin injection efficiency can be improved.

[0073] In addition, as preferred examples, the material and thickness (preferable range) of each layer are as follows.

[0074] Contact metal layer 8: Ru; 5 nm; (3 nm to 8 nm)

[0075] Protective non-magnetic metal layer 7: Ag; 5 nm; (3 nm to 8 nm)

[0076] Second ferromagnetic layer 6: CMS (cobalt manganese silicon alloy); 5 nm; (3 nm to 20 nm)

[0077] · Second intermediate layer 5C: NiAlX alloy (the above-mentioned Ni γ1 Al γ2 X γ3 ); 1nm; (0.1nm or more and 15nm or less)

[0078] Non-magnetic metal layer 5B: Ag; 5 nm; (3 nm to 10 nm)

[0079] · First intermediate layer 5A: NiAlX alloy (the above-mentioned Ni γ1 Al γ2 X γ3 ); 1nm; (0.1nm or more and 15nm or less)

[0080] First ferromagnetic layer 4: CMS (cobalt manganese silicon alloy); 10 nm; (3 nm to 20 nm)

[0081] Second non-magnetic metal layer 3: Ag; 50 nm; (20 nm to 100 nm)

[0082] First non-magnetic metal layer 2: Cr; 20 nm; (10 nm to 30 nm)

[0083] Substrate 1: MgO; 0.5 mm; (0.1 mm or more and 2 mm or less)

[0084] Furthermore, the thickness of each layer is not limited to the above range unless it is used for a magnetoresistive effect element.

[0085] Next, examples of materials for the layers constituting the magnetoresistive element will be further described.

[0086] Ru can be suitably used as the contact metal layer 8, but in addition thereto, it may also include one or more metal elements selected from, for example, Ru, Ag, Al, Cu, Au, Cr, Mo, Pt, W, Ta, Pd and Ir; alloys of these metal elements; or a stacked structure of materials composed of two or more of these metal elements.

[0087] Ag can be suitably used as the protective non-magnetic metal layer 7, but in addition thereto, it may also include a layered structure of a material consisting of one or more metal elements selected from, for example, Ru, Ag, Al, Cu, Au, Cr, Mo, Pt, W, Ta, Pd and Ir; an alloy of these metal elements; or a material consisting of two or more of these metal elements.

[0088] As the second ferromagnetic layer 6, CMS (Co2L) which is a Heusler alloy can be preferably used. α M β ), but in addition thereto, it may also contain Heusler alloys such as Co2MnGe, Co2MnGa, Co2FeGa, Co2FeSi, Co2MnSn, Co2MnAl, Co2FeAl, Co2CrAl, Co2VAl, Co2MnGaSn, Co2FeGeGa, Co2MnGeGa, Co2FeGaSi, Co2FeGeSi, Co2CrIn, Co2CrSn, or ferromagnetic materials such as Fe3O4, CrO2, and CoFeB, or may be substantially composed of such ferromagnetic materials. In addition, for Co2L α M β When the number of Co atoms is 2, the ratio of the number of L atoms constituting the entire alloy is represented by α, and the ratio of the number of M atoms is represented by β.

[0089] As the first ferromagnetic layer 4, CMS (Co2L) which is a Heusler alloy can be preferably used. αM β ), but in addition to this, it can also include Heusler alloys such as Co2MnGe, Co2MnGa, Co2FeGa, Co2FeSi, Co2MnSn, Co2MnAl, Co2FeAl, Co2CrAl, Co2VAl, Co2MnGaSn, Co2FeGeGa, Co2MnGeGa, Co2FeGaSi, Co2FeGeSi, Co2CrIn, Co2CrSn, or ferromagnetic materials such as Fe3O4, CrO2, CoFeB, or can essentially be composed of such ferromagnetic materials.

[0090] Ag can be preferably used as the second non-magnetic metal layer 3. However, in addition thereto, at least one metal element selected from Ag, Au, Cu, Cr, V, Al, W, and Pt may be included. An alloy of these metal elements or a laminated structure of materials composed of two or more of these metal elements may also be included. Examples of metal element alloys include cubic AgZn alloys, AgMg alloys, and NiAl alloys.

[0091] Cr can be preferably used as the first non-magnetic metal layer 2. However, in addition to this, at least one metal element selected from Ag, Au, Cu, Cr, V, Al, W, and Pt may be included to control the crystal orientation of the upper layer. An alloy of these metal elements or a laminated structure of materials composed of two or more of these metal elements may also be included. Examples of metal element alloys include cubic AgZn alloys, AgMg alloys, and NiAl alloys.

[0092] MgO is preferably used as the substrate 1, but other materials are not particularly limited, as long as they have appropriate mechanical strength and are suitable for heat treatment or microfabrication, such as metal oxide single crystal substrates, silicon single crystal substrates, silicon single crystal substrates with thermal oxide films, sapphire single crystal substrates, ceramics, quartz, and glass. Substrates containing MgO single crystal facilitate the formation of epitaxial films, which can exhibit high magnetoresistance properties.

[0093] Next, the advantages of the above-mentioned structure over the comparative example will be described.

[0094] Figure 2 It is a front view of a magnetoresistive effect element MR according to a comparative example.

[0095] The basic structure of the magnetoresistive element according to the comparative example is Figure 1 The structure shown is the structure except for the intermediate layers (first intermediate layer 5A, second intermediate layer 5C) made of NiAlX alloy. The other structures are the same as those shown in FIG. Figure 1 The structures represented are the same.

[0096] Figure 3 It represents that in the structure of the above embodiment (the structure of the preferred embodiment), in the general formula (1): Ni γ1 Al γ2 X γ3 Graph showing the relationship between γ and the thickness (nm) of the non-sensitive layer in the intermediate layer.

[0097] Figure 3 What is indicated is Figure 1 In the structure, only the non-magnetic metal layer 5B, the intermediate layer 5C, and the second ferromagnetic layer 6 are formed on the first base layer 1 to form a stacked structure, and Co2Mn 1.0 Si 1.0 In the case of the second ferromagnetic layer 6 (Example R), the nonmagnetic metal layer 5B, the intermediate layer 5C, and the second ferromagnetic layer 6 are stacked in this order directly on the first base layer 1. The materials and thicknesses of the layers are as follows.

[0098] · Second ferromagnetic layer 6: Co2Mn 1.0 Si 1.0 ; 10nm

[0099] · Second intermediate layer 5C: Ni γ1 Al γ2 X γ3 ; 10nm

[0100] Non-magnetic metal layer 5B: Ag; 100 nm

[0101] ·1st base material layer 1: MgO; 0.5mm

[0102] Furthermore, as Comparative Example A, a laminated structure was prepared by removing only the intermediate layer from Example R. The materials and thicknesses were as follows.

[0103] · Second ferromagnetic layer 6: Co2Mn 1.0 Si 1.0 ; 10nm

[0104] · Second intermediate layer 5C: None

[0105] Non-magnetic metal layer 5B: Ag; 100 nm

[0106] ·1st base material layer 1: MgO; 0.5mm

[0107] As described above, in Comparative Example A, the non-inductive layer is 0.8 nm thick. However, in Example R, when X=Si, Sc, Ti, Cr, Mn, Fe, Co, Cu, Zr, Nb, or Ta is used, the thickness of the non-inductive layer is reduced. The laminated structure of Example R includes the NiAlX alloy represented by the aforementioned general formula (1) in a manner that minimizes the lattice mismatch between the ferromagnetic layer 6 and the non-magnetic metal layer 5B, compared to the case where the ferromagnetic layer and the non-magnetic metal layer are in direct contact (Comparative Example A). Therefore, this laminated structure reduces the non-inductive layer within the ferromagnetic and non-magnetic metal layers. In this case, the presence of the intermediate layer 5C alleviates the lattice mismatch between the non-magnetic metal layer 5B and the ferromagnetic layer 6, and the improved crystallinity reduces the area of ​​the non-inductive layer. Therefore, the area of ​​the magnetic interaction is increased, thereby improving the MR ratio and spin injection efficiency. In particular, when γ is within the aforementioned range (0 < γ < 0.5), the area of ​​the non-inductive layer is particularly small.

[0108] Furthermore, when γ is within the aforementioned range (0 < γ < 0.3), the area of ​​the non-inductive layer is further reduced, thereby improving the MR ratio and spin injection efficiency. Furthermore, in this laminated structure, the crystal structure of the NiAlX alloy layer is stable, achieving a face-centered cubic lattice structure. As a result, the lattice mismatch between the ferromagnetic layer and the non-magnetic metal layer is mitigated, and the area of ​​the non-inductive layer can be reduced.

[0109] Furthermore, when X in the intermediate layer (NiAlX alloy layer) is an element selected from Si, Cr, Fe, Co, and Zr, the relationship between the lattice constant correspondence reference value of the ferromagnetic layer ≤ the lattice constant correspondence reference value of the NiAlX alloy layer ≤ the lattice constant correspondence reference value of the non-magnetic metal layer, or the lattice constant correspondence reference value of the ferromagnetic layer ≥ the lattice constant correspondence reference value of the NiAlX alloy layer ≥ the lattice constant correspondence reference value of the non-magnetic metal layer, is established. This alleviates the lattice mismatch between the ferromagnetic and non-magnetic metal layers. The lattice constant correspondence reference value here refers to either the lattice constant a or twice a when the crystal planes are aligned at a 0-degree inclination; and to a times the square root of 2 when the crystal planes are aligned at a 45-degree inclination. Consequently, this laminated structure reduces the size of the inductive layer in the ferromagnetic and non-magnetic metal layers. Furthermore, the aforementioned relationship between the lattice constants holds true even when the number of selected elements is one or more.

[0110] In addition, the thickness of the non-inductive layer was also studied when the intermediate layer and the ferromagnetic layer were changed.

[0111] Figure 4This is a graph showing the thickness of the non-inductive layer and the like in magnetoresistive elements (Comparative Example 1, Examples 1 to 5) when various materials are used.

[0112] exist Figure 1 In the structure of Examples 1 to 5, a laminated structure is constructed by forming only the non-magnetic metal layer 5B, the intermediate layer 5C, and the second ferromagnetic layer 6 on the first base layer 1. In other words, the non-magnetic metal layer 5B, the intermediate layer 5C, and the second ferromagnetic layer 6 are laminated structures formed directly on the first base layer 1 in this order. The materials and thicknesses of each layer are as follows.

[0113] (Example 1)

[0114] Second ferromagnetic layer 6: Co2TiSn; 5nm

[0115] Second intermediate layer 5C: NbNi2Al; 50nm

[0116] Non-magnetic metal layer 5B: Cu; 50nm

[0117] ·Substrate 1: MgO; 0.5mm

[0118] (Example 2)

[0119] · Second ferromagnetic layer 6: Co2Mn 1.3 Si 0.95 ; 5nm

[0120] Second intermediate layer 5C: NbNi2Al; 50nm

[0121] Non-magnetic metal layer 5B: Cu; 50nm

[0122] ·Substrate 1: MgO; 0.5mm

[0123] (Example 3)

[0124] · Second ferromagnetic layer 6: Co2Mn 1.3 Si 0.95 ; 5nm

[0125] Second intermediate layer 5C: NbNi2Al; 50nm

[0126] Non-magnetic metal layer 5B: Ag; 50nm

[0127] ·Substrate 1: MgO; 0.5mm

[0128] (Example 4)

[0129] · Second ferromagnetic layer 6: Co2Mn 1.3 Si 0.95 ; 5nm

[0130] · Second intermediate layer 5C: Cr 0.66 Ni 0.67 Al 0.67 ;50nm

[0131] Non-magnetic metal layer 5B: Ag; 50nm

[0132] ·Substrate 1: MgO; 0.5mm

[0133] (Example 5)

[0134] · Second ferromagnetic layer 6: Co2Mn 1.3 Si 0.95 ; 5nm

[0135] Second intermediate layer 5C: CrNi2Al; 50nm

[0136] Non-magnetic metal layer 5B: Ag; 50nm

[0137] ·Substrate 1: MgO; 0.5mm

[0138] Comparative Example 1 is Figure 2 In the structure of , only the non-magnetic metal layer 5B and the second ferromagnetic layer 6 are formed on the substrate 1. In other words, the non-magnetic metal layer 5B and the second ferromagnetic layer 6 are formed on the substrate 1 in this order. The materials and thicknesses of the layers are as follows.

[0139] (Comparative Example 1)

[0140] Second ferromagnetic layer 6: Co2TiSn; 5nm

[0141] Non-magnetic metal layer 5B: Cu; 50nm

[0142] ·Substrate 1: MgO; 0.5mm

[0143] according to Figure 4 The results can reveal the following:

[0144] The thickness t2 of the non-inductive layer of Example 1 is smaller than the thickness t2 of the non-inductive layer of Comparative Example 1. The crystal quality is improved by using the intermediate layer.

[0145] The thickness t2 of the non-inductive layer of Example 2 is the same as the thickness t2 of the non-inductive layer of Example 1 and is smaller than that of Comparative Example 1, and the crystal quality is excellent.

[0146] The thickness t2 of the non-inductive layer in Example 3 shows that the thickness t2 of the non-inductive layer becomes significantly smaller than that in Example 2 by setting the non-magnetic metal layer to Ag having a lattice constant close to that of the NiAlX alloy layer.

[0147] The thickness t2 of the non-inductive layer in Example 4 is smaller than the thickness t2 of the non-inductive layer in Example 3. The crystal quality is improved by changing the material of the intermediate layer.

[0148] The thickness t2 of the non-inductive layer of Example 5 is smaller than the thickness t2 of the non-inductive layer of Example 4. The crystal quality is further improved by changing the composition of the material of the intermediate layer.

[0149] Next, the thickness t1 of the intermediate layer 5C will be discussed.

[0150] Figure 5 Graph showing the relationship between the thickness t1 (nm) of the intermediate layer 5C and the thickness t2 (nm) of the non-sensitive layer in Example A group. Figure 6 Graph showing the relationship between the thickness t1 (nm) of the intermediate layer 5C and the thickness t2 (nm) of the non-sensitive layer in Example A group.

[0151] The Example A group has the same structure as that of Example 5 except that the thickness t1 of the intermediate layer 5C is changed, and has the following materials and thicknesses.

[0152] (Example A Group)

[0153] · Second ferromagnetic layer 6: Co2Mn 1.3 Si 0.95 ; 5nm

[0154] Second intermediate layer 5C: CrNi2Al (0.1nm~50nm)

[0155] Non-magnetic metal layer 5B: Ag; 50nm

[0156] ·Substrate 1: MgO; 0.5mm

[0157] In this stacked structure, when the thickness of the intermediate layer 5C (NiAlX alloy layer) is set to t1, t1 preferably satisfies the following relational expression.

[0158] 0.2nm≤t1≤10nm

[0159] Specifically, when t1 ≤ 10 nm, spin scattering is further reduced for electrons moving from and to the ferromagnetic layer. Furthermore, when t1 ≤ 0.2 nm, the lattice mismatch between the ferromagnetic layer and the nonmagnetic metal layer is further reduced, resulting in a smaller thickness t2 of the non-inductive layer within the ferromagnetic and nonmagnetic metal layers.

[0160] Next, the compositions (α, β) of the ferromagnetic layers ( 4 , 6 ) will be examined.

[0161] Figure 7The Co2L that constitutes the ferromagnetic layers (4, 6) in the Example B group α M β Graph showing the relationship between various parameters (α+β, α, β) and MR ratio (%) (β=0.95) in (L=Mn, M=Si).

[0162] Example B group has Figure 1 The structure has the following materials and thicknesses, except for the change in the composition of the ferromagnetic layer. β is fixed at 0.95, and α is varied within the range of 0.5 to 1.8.

[0163] Contact metal layer 8: Ru; 5nm

[0164] Protective non-magnetic metal layer 7: Ag; 5nm

[0165] Second ferromagnetic layer 6: Co2L α M β (L=Mn,M=Si); 5nm

[0166] Second intermediate layer 5C: CrNi2Al; 1nm

[0167] Non-magnetic metal layer 5B: Ag; 5nm

[0168] First intermediate layer 5A: CrNi2Al; 1nm

[0169] ·First ferromagnetic layer 4: Co2L α M β (L=Mn,M=Si); 10nm

[0170] Second non-magnetic layer 3: Ag; 50nm

[0171] ·1st non-magnetic metal layer 2: Cr; 20nm

[0172] ·Substrate 1: MgO; 0.5mm

[0173] Figure 8 The ferromagnetic layer (Co2L α M β ) is a graph showing the relationship between various parameters (α+β, α, β) and MR ratio (%) (α=1.3).

[0174] Example C group has Figure 1 The structure of the embodiment B group has the same materials and thickness as those of the embodiment B group except that the composition of the ferromagnetic layer is changed. α is fixed at 1.3, and β is varied within the range of 0.55 to 1.45.

[0175] The ferromagnetic layers (4, 6) include a Heusler alloy represented by the following general formula (2) when L is Mn, M is Si, and α and β are positive values.

[0176] Co2L α M β ……(2)

[0177] When the ferromagnetic layers (4, 6) are made of a Heusler alloy, since the lattice constants of the NiAlX alloys are close, the crystallinity is improved and the spin injection efficiency is increased.

[0178] Figure 9 This is a graph showing the relationship between α+β and MR ratio (%) in Example B group and Example C group.

[0179] from Figure 9 You can learn the following content.

[0180] In the Heusler alloy represented by the general formula (2), α and β preferably satisfy the following relational expressions (2-1), (2-2), and (2-3).

[0181] 0.7<α<1.6……(2-1)

[0182] 0.65<β<1.35……(2-2)

[0183] 2<α+β<2.6……(2-3)

[0184] According to this stacked structure, since 0.7 < α < 1.6 and 0.65 < β < 1.35, the Heusler alloy serving as the ferromagnetic layers (4, 6) has a lattice constant close to that of a stoichiometric composition, and has good lattice matching with the NiAlX alloy. Furthermore, since 2 < α + β < 2.6, the Heusler alloy serving as the NiAlX alloy serving as the ferromagnetic layer easily maintains half-metallic properties and can achieve a large magnetoresistance effect (MR ratio).

[0185] Furthermore, in the ferromagnetic layers (4, 6), when L is set to one or more elements selected from Mn and Fe; M is set to one or more elements selected from Si, Al, Ga and Ge; and α and β are set to positive values, the ferromagnetic layers (4, 6) can include the following general formula (2): Co2L α M β ...(2) Heusler alloy shown. As described above, when the ferromagnetic layers (4, 6) are Heusler alloys, the crystallinity becomes higher and the spin injection efficiency becomes higher.

[0186] In addition, when L and M are the above-mentioned elements, the Heusler alloy serving as the ferromagnetic layer has a lattice constant corresponding reference value close to that of the NiAlX alloy layer represented by general formula (1). In addition, the number of the above-mentioned elements is not 1, because even if it is 1 or more, it is easy to infer that it has a lattice constant close to that of the NiAlX alloy layer, so the crystallinity and magnetic quality of the ferromagnetic layer can be well maintained. As a result, the non-inductive layer in the ferromagnetic layer and the non-magnetic metal layer can be further reduced. In addition, the so-called lattice constant corresponding reference value here refers to either the lattice constant a or a value twice a when each crystal plane is matched at a 0-degree tilt, and is a value multiplied by the square root of 2 when matching at a 45-degree tilt.

[0187] Furthermore, from the same viewpoint as above, the following ranges are more preferred.

[0188] 0.8≤α≤1.5……(2-1')

[0189] 0.75≤β≤1.25……(2-2')

[0190] 2.05≤α+β≤2.55……(2-3')

[0191] Next, the lattice constant of each layer is examined.

[0192] Figure 1 The nonmagnetic metal layer 5B shown is Ag, and the first and second intermediate layers 5A and 5C are NiAlX alloys, where X is an element selected from Si, Sc, Ti, Cr, Mn, Fe, Co, Cu, Zr, Nb, and Ta. X can be one of these elements, or it can contain two or more elements (X1, X2). In this case, the lattice constant can be approximately midway between the lattice constant when X1 is used and the lattice constant when X2 is used. The value of γ is within the range of 0 < γ < 0.5.

[0193] exist Figure 10 as well as Figure 11 In the figure, NiAlSi, NiAl 0.75 Si 0.25 、ScNi2Al、TiNi2Al、TiNi 0.25 Al 2.75 、CrNi2Al、Cr 0.66 Ni 0.67 Al 0.67 、MnNi2Al、Mn 0.5 Ni 0.5 Al, Fe2NiAl, Co 0.5 Ni 0.5 Al, Cu0.4 Ni 0.6 Al, ZrNi2Al, ZrNi 0.48 Al 2.52 The lattice constants a, 2a, and the square root of a times 2 of NbNi2Al and TaNi2Al, the crystal structure type, and the Pearson symbol. When the intermediate layer (5A, 5C) is grown with the crystal axis rotated 45° with respect to the perpendicular direction of the adjacent ferromagnetic layer (4, 6), the square root of a times 2 becomes close to the lattice constant of the ferromagnetic layer. Alternatively, twice the lattice constant of the intermediate layer (2a) may also become close to the lattice constant of the ferromagnetic layer. The (*) in the same figure indicates a value close to the lattice constant of the adjacent ferromagnetic layer (4, 6). To achieve lattice matching, the values ​​of a, 2a, or the square root of a times 2 marked with (*) are selected.

[0194] Figure 12 This is a graph showing the lattice constants of the ferromagnetic layers (4, 6) (various Heusler alloys).

[0195] The same figure shows Co2MnSi, Co2MnGe, Co2MnGa, Co2FeGa, Co2FeSi, Co2MnSn, Co2MnAl, Co2FeAl, Co2CrAl, Co2VAl, Co2MnGa 0.5 Sn 0.5 , the lattice constant a of Co2FeGeGa.

[0196] Figure 13 、 Figure 14 、 Figure 15 as well as Figure 16 This is a graph showing the lattice mismatch ratio between Ag (non-magnetic metal layer) or NiAlX alloy (intermediate layer) and various Heusler alloys (ferromagnetic layer).

[0197] Here, the lattice mismatch ratio = [(lattice constant a of Ag or the intermediate layer, 2a, or the value of a multiplied by the square root of 2 - lattice constant of the ferromagnetic layer) / lattice constant of the ferromagnetic layer].

[0198] Among these material combinations, those with a low lattice mismatch can increase the MR ratio. Specifically, by using a NiAlX alloy (intermediate layer) with a lattice mismatch smaller than that of Ag (non-magnetic metal layer) and various Heusler alloys (ferromagnetic layer), the non-inductive layer can be reduced and the MR ratio can be improved. Because dissimilar materials are bonded together, the absolute value of the lattice mismatch is greater than zero. The lattice constants are values ​​at room temperature (300K).

[0199] Furthermore, the non-magnetic metal layer 5B can contain one or more elements selected from Ag, Cr, Al, Au, and NiAl. This non-magnetic metal layer can easily suppress the diffusion of element X into the non-magnetic metal layer. It is not necessary to have only one element with a small diffusion constant relative to element X; it is believed that the diffusion suppression effect can be achieved if one or more elements are included. Furthermore, these materials can also bring the lattice constant closer to that of the intermediate layer.

[0200] Figure 17 It is a diagram showing a cross-sectional structure of a playback portion of a magnetic head having a magnetoresistive element.

[0201] The magnetic head has Figure 1 The magnetoresistive element MR is shown. Specifically, the magnetic head comprises a lower magnetic shield 21, a magnetoresistive element MR fixed to the magnetic shield, an upper magnetic shield 22 fixed above the magnetoresistive element MR, and side magnetic shields 23 fixed around the upper magnetic shield 22. The magnetic shields are made of NiFe or other materials. A magnetic head of this structure is well known and described in U.S. Patent No. 5,695,697, which can be referenced.

[0202] Figure 18 It is a diagram showing a cross-sectional structure of a magnetic head including a magnetoresistive element MR.

[0203] This magnetic recording head includes a main magnetic pole 61, a return magnetic pole 62, and a spin torque oscillator (oscillator) 10 provided on the main magnetic pole 61. The spin torque oscillator 10 has the same structure as the magnetic head described above, and has a structure in which a lower magnetic shield 21 and an upper magnetic shield 22 are arranged as electrodes above and below the magnetoresistive element MR.

[0204] Since the coil 63 is wound around the base end of the main magnetic pole 61, if the driving current is supplied to the current source I R , a write magnetic field is generated around the main magnetic pole 61. The generated magnetic field forms a closed magnetic circuit through the magnetic pole.

[0205] When a direct current flows between the upper and lower electrodes of the spin-torque oscillator 10, which includes the magnetoresistive element MR, the spin torque generated in the spin injection layer causes ferromagnetic resonance, generating a high-frequency magnetic field from the spin-torque oscillator 10. High-density magnetic recording is performed only in the portion where the recording magnetic field generated by the main magnetic pole 61 and the high-frequency magnetic field generated by the spin-torque oscillator 10 overlap, with respect to the magnetic recording medium 80 facing these areas. A magnetic recording head having such a structure is well known and is described in Japanese Patent No. 5173750, which can be referenced.

[0206] Figure 19 A diagram showing the structure of a current sensor including a plurality of magnetoresistive effect elements.

[0207] This current sensor is constructed from a bridge circuit consisting of multiple magnetoresistive elements (MR) electrically connected. In the figure, four magnetoresistive elements (MR) form the bridge circuit. Two circuit trains, each consisting of two magnetoresistive elements (MR) connected in series, are connected in parallel between ground and power supply potential (Vdd). The connection point between the two magnetoresistive elements (MR) becomes the first output terminal (Out1) and the second output terminal (Out2), respectively. The voltage between these terminals becomes the output signal.

[0208] When the wire being measured is extended along the Z-axis, a magnetic field is generated around the wire. The resistance of the magnetoresistive element (MR) changes according to the magnitude of the magnetic field. The magnitude of the output signal corresponds to the magnitude of the magnetic field, that is, the amount of current flowing through the wire, allowing the device to function as a current sensor. Furthermore, the device can function as a magnetic sensor that directly detects the magnitude of the magnetic field.

[0209] Figure 20 This is a diagram showing the structure of a high-frequency filter including a plurality of magnetoresistive effect elements.

[0210] A high-frequency filter is one in which multiple magnetoresistive elements MR are electrically connected in parallel. Specifically, the upper electrodes (shield electrodes or contact electrodes) of the magnetoresistive elements MR are connected to one another, or, if common, the lower electrodes (shield electrodes or first non-magnetic metal layers) of the magnetoresistive elements MR are connected to one another or made common.

[0211] Because the multiple magnetoresistive elements MR have different horizontal cross-sectional areas (cross-sectional areas in the XY plane), their resonant frequencies differ. When a high-frequency signal is input to the input terminal In, each magnetoresistive element MR absorbs the signal component of the input high-frequency signal that has a frequency equal to its own resonant frequency and outputs the remaining high-frequency signal component from the output terminal Out. Thus, the device functions as a high-frequency filter. This device is well known and is described, for example, in Japanese International Publication No. WO2011 / 033664, which can be referenced.

[0212] in addition, Figure 1 The magnetoresistance effect element can be manufactured in the following form.

[0213] First, a first nonmagnetic metal layer 2, a second nonmagnetic metal layer 3, a first ferromagnetic layer 4, a nonmagnetic spacer layer 5, a second ferromagnetic layer 6, a protective nonmagnetic metal layer 7, and a contact metal layer 8 are sequentially deposited on a substrate 1. Furthermore, the nonmagnetic spacer layer 5 is formed by depositing a first intermediate layer 5A, a nonmagnetic metal layer 5B, and a second intermediate layer 5C on the first ferromagnetic layer 4.

[0214] Deposition is performed using a well-known technique, namely sputtering. In this embodiment, each layer is formed at room temperature using a sputtering target made of the constituent materials of each layer and an ultra-high vacuum sputtering device. However, two or more sputtering targets can also be used simultaneously. That is, by using two (or more) targets made of different materials A and B and sputtering the targets simultaneously, the alloy film of A and B or the material composition of each layer can be adjusted. For example, by sputtering a NiAl target and a target made of another metal X simultaneously, a metal film can be formed. Commercially available products can be used as the substrate material; MgO, a commercial product from Japan, was used as the substrate 1 described above. Furthermore, the first ferromagnetic layer 4 is annealed at 500°C after film formation. The second ferromagnetic layer 6 is annealed at 450°C after film formation. The magnetoresistive element can be finely processed by electron beam lithography and Ar ion milling to a shape that allows evaluation of magnetoresistive properties. In addition, methods for producing CMS using a sputtering device are described in, for example, U.S. Patent Application Publication No. 2007 / 0230070, U.S. Patent Application Publication No. 2013 / 0229895, U.S. Patent Application Publication No. 2014 / 0063648, U.S. Patent Application Publication No. 2007 / 0211391, and U.S. Patent Application Publication No. 2013 / 0335847.

[0215] Figure 21 This is shown as Example 6. Figure 1 The graph of materials, lattice constants, film thickness, and MR ratio (%) under the deformation condition is not shown in the structure and Figure 1 The first intermediate layer 5A and the second intermediate layer 5C are made into a stacked structure of NiAl alloy and NiAlX alloy. In addition, NiAlX alloy is stacked between NiAl alloy, NiAl alloy and ferromagnetic layer in a form of contact with non-magnetic metal layer 5B. Co2Mn is used as the first ferromagnetic layer 4 and the second ferromagnetic layer 6. 1.0 Si 0.95 , other materials and film thicknesses are as described below.

[0216] Contact metal layer 8: Ru; 5nm

[0217] Protective non-magnetic metal layer 7: Ag; 5nm

[0218] Second ferromagnetic layer 6: CMS (cobalt manganese silicon alloy); 5 nm

[0219] Second intermediate layer 5C: a stack of NiAl alloy and NiAlX alloy (NiAl alloy on the non-magnetic metal layer 5B side); 0.5 nm each, 1 nm in total

[0220] Non-magnetic metal layer 5B: Ag; 5nm

[0221] First intermediate layer 5A: a stack of NiAl alloy and NiAlX alloy (NiAl alloy on the non-magnetic metal layer 5B side); 0.5 nm each, 1 nm in total

[0222] First ferromagnetic layer 4: CMS (cobalt manganese silicon alloy); 10 nm

[0223] Second non-magnetic metal layer 3: Ag; 50nm

[0224] ·1st non-magnetic metal layer 2: Cr; 20nm

[0225] ·Substrate 1: MgO; 0.5mm

[0226] like Figure 21 When the composition of the intermediate layer changes along the thickness direction, the MR ratio increases from 10.1% to 12.3%. Here, the lattice constant (corresponding to the reference value) of the ferromagnetic layer CMS (cobalt-manganese-silicon alloy) is 0.5606 nm, the lattice constant (corresponding to the reference value) of the intermediate layer CrNi2Al is 0.5737 nm, the lattice constant (corresponding to the reference value) of the non-magnetic metal layer Ag is 0.5798, and the lattice constant (corresponding to the reference value) of the NiAlX alloy with γ = 0 (i.e., NiAl alloy) is 0.5760. Therefore, in terms of the magnitude of the lattice constants, by interposing the NiAlX alloy with γ = 0, i.e., a NiAlX alloy with low γ, between the non-magnetic metal layer and the NiAlX alloy, the lattice constant (corresponding to the reference value) changes continuously along the thickness direction of the intermediate layer, further improving the crystal quality of the ferromagnetic layer and the non-magnetic metal layer. This, in turn, improves the MR ratio. The lattice constant corresponding reference value here refers to either the lattice constant a or a value twice a when each crystal plane is matched at a tilt of 0 degrees, and refers to a times the square root of 2 when matching at a tilt of 45 degrees.

[0227] Therefore, the value of γ3 can be reduced as the distance from the ferromagnetic layer (4, 6) is increased along the thickness direction. In this stacked structure, compared to a stacked structure consisting solely of ferromagnetic layers, the lattice mismatch between the ferromagnetic layers (4, 6) and the non-magnetic metal layer 5B is reduced because the X element concentration in the intermediate layers (5A, 5C) (NiAlX alloy layer) represented by general formula (1) is higher on the ferromagnetic layer side. Furthermore, because the X element concentration is lower on the non-magnetic metal layer 5B side, the lattice mismatch between the ferromagnetic layers (4, 6) and the non-magnetic metal layer 5B is further reduced. Therefore, with this stacked structure, the non-inductive regions in the ferromagnetic and non-magnetic metal layers are reduced, and the MR ratio can be improved. Furthermore, the value of γ3 can be varied along the in-plane direction or the thickness direction. By setting the value of γ3 to mitigate the local lattice mismatch and varying the X element concentration according to the degree of local lattice mismatch, it is expected that the quality of the ferromagnetic and non-magnetic metal layers will ultimately be improved.

[0228] As described above, the stacked structure and the magnetoresistive element are stacked structures located on the non-magnetic metal layer 5B, and include a ferromagnetic layer 6 and an intermediate layer 5C between the non-magnetic metal layer 5B and the ferromagnetic layer 6. The intermediate layer 5C includes a general formula (1): Ni γ1 Al γ2 X γ3 ...(1) [X represents one or more elements selected from Si, Sc, Ti, Cr, Mn, Fe, Co, Cu, Zr, Nb, and Ta, and in the case of γ = γ3 / (γ1+γ2+γ3), 0 < γ < 0.5] represents a NiAlX alloy layer, and it is possible to reduce the non-inductive layer and obtain a high MR ratio. A magnetic head, sensor, high-frequency filter, or oscillator including any of the above magnetoresistive elements can exhibit excellent characteristics due to its large magnetoresistive effect.

[0229] Furthermore, in principle, the spin-related behavior of the magnetoresistive element in the above-described structure is believed to be similar not only in CPP-GMR elements but also in CIP-GMR elements (in-plane current-type GMR elements). Therefore, from the perspective of improving the MR ratio, the above-described structure is also considered effective in CIP-GMR elements. Furthermore, since the area of ​​the non-sensitive layer is reduced in any element that utilizes magnetism, the stacked structure can also be applied to applications other than magnetoresistive elements (such as spin Hall effect / inverse spin Hall effect, and spin transfer torque).

Claims

1. A magnetoresistive effect element, characterized in that: have: The first ferromagnetic layer, The second ferromagnetic layer, and a non-magnetic spacer layer disposed between the first ferromagnetic layer and the second ferromagnetic layer, The non-magnetic spacer layer includes a non-magnetic metal layer and at least one of a first intermediate layer provided below the non-magnetic metal layer and a second intermediate layer provided above the non-magnetic metal layer, and at least one of the first intermediate layer and the second intermediate layer is in contact with the non-magnetic metal layer. The first intermediate layer and the second intermediate layer include a NiAlX alloy layer represented by the following general formula (1): We γ1 To γ2 X γ3 ……(1) X represents one or more elements selected from Si, Sc, Ti, Cr, Mn, Fe, Co, Cu, Zr, Nb, and Ta, and when γ = γ3 / (γ1 + γ2 + γ3), 0 < γ < 0.5 is satisfied. The value of γ3 varies along the in-plane direction or the thickness direction.

2. The magnetoresistive element according to claim 1, wherein: L is set to one or more elements selected from Mn and Fe; M is set to one or more elements selected from Si, Al, Ga, and Ge; When α and β are set to positive values, The ferromagnetic layer includes a Heusler alloy represented by the following general formula (2): Co2L α M β (2)。 3. The magnetoresistive element according to claim 1 or 2, wherein: The value of γ3 decreases as one moves away from the ferromagnetic layer in the thickness direction thereof.

4. The magnetoresistive effect element according to claim 1 or 2, wherein: The non-magnetic metal layer includes one or more selected from the group consisting of Ag, Cr, Al, Au, and NiAl.

5. The magnetoresistive effect element according to claim 1 or 2, wherein: X in the NiAlX alloy layer is one or more elements selected from Si, Cr, Fe, Co, and Zr.

6. The magnetoresistive effect element according to claim 1 or 2, wherein: In the general formula (1), 0<γ<0.3 is satisfied.

7. The magnetoresistive effect element according to claim 1 or 2, wherein: When the thickness of the NiAlX alloy layer is set to t1, Satisfies 0.2nm≤t1≤10nm.

8. The magnetoresistive element according to claim 2, wherein: In the Heusler alloy represented by the general formula (2), α and β satisfy the following relationships (2-1), (2-2), and (2-3): 0.7＜α＜1.6……（2-1）； 0.65＜β＜1.35……（2-2）； 2＜α+β＜2.6……（2-3）。 9. A magnetic head, characterized in that: A magnetoresistive effect element according to any one of claims 1 to 8 is provided.

10. A sensor, characterized in that: A magnetoresistive effect element according to any one of claims 1 to 8 is provided.

11. A high-frequency filter, characterized in that: A magnetoresistive effect element according to any one of claims 1 to 8 is provided.

12. An oscillator, characterized in that: A magnetoresistive effect element according to any one of claims 1 to 8 is provided.

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